Bit-Reproducible infrastructure could also result in some of the wildest build distribution architectures if you think about it. You could publish sources and have people register like in APT mirrors to provide builds, and at the end of the day, the build from the largest bit-equal group is published.

I do see the Tor-Issue - a botnet or a well-supplied malicious actor could just flood it. And if you flip it - if you'd need agreement about the build output, it could also be poisoned with enough nodes to prevent releases for a critical security issue. I agree, I don't solve all supply chain issues in one comment :)

But that in turn could be helped with reputation. Maybe a node needs to supply 6 months of perfect builds - for testing as well - to become eligible. Which would be defeated by patience, but what isn't? It'd just have to be more annoying to breach the distributed build infrastructure than to plant a malicious developer.

This combination of reproducible, deterministic builds, tests across a number of probably-trustworthy sources is quite interesting, as it allows very heavy decentralization. I could just run an old laptop or two here to support. And then come compromise hundreds of these all across the world.